An image forming apparatus such as a copying machine and a printer utilizing electrophotographic method is provided with an electrophotographic photosensitive member. In such image forming apparatus, the electrophotographic photosensitive member is rotated by a power transmitter, and synchronously with the rotation, operations such as electrification, exposure, development, transfer, and cleaning are repeated, thereby forming an image on a recording medium.
Specifically, in the image forming apparatus, the electrophotographic photosensitive member is electrically charged at its surface and then rotated while being irradiated by laser light for exposure, according to an image pattern, so that an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member. Next, the latent image is developed by attaching toner to the photosensitive member. The toner attached to the electrophotographic photosensitive member is transferred to a recording medium. After the transfer of toner to the recording medium, the electrophotographic photosensitive member is rotated while a cleaning blade is pressed onto the surface of electrophotographic photosensitive member, so that remaining toner is removed.
The electrophotographic photosensitive member includes a metal cylindrical body on which a photosensitive layer is formed. The photosensitive layer includes a photoconductive layer formed on the cylindrical body using inorganic material, and a surface layer formed using inorganic material to coat the photoconductive layer. In such electrophotographic photosensitive member, thickness of the photoconductive layer and the surface layer is normally set to be substantially constant in the axial direction of the entire cylindrical body. Here, “substantially constant” means that a ratio (Te:Tc) of thickness (Tc) at the middle portion of the body to thickness (Te) at one end or the other end of the body is not more than 1.001:1.